I. Field
The present disclosure relates generally to communication, and more specifically to techniques for performing system selection and acquisition by a wireless device.
II. Background
Wireless communication systems are widely deployed to provide various communication services such as voice, packet data, and so on. These wireless systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources. Examples of such multiple-access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, and Frequency Division Multiple Access (FDMA) systems. A CDMA system may implement one or more CDMA standards such as IS-2000 and IS-95 (commonly called “1x-EV-DV”, or simply “1x”), IS-856 (commonly called “1x-EV-DO”), and so on, which are known in the art.
A wireless device (e.g., a cellular phone) that supports 1x and/or 1x-EV-DO typically maintains a preferred roaming list (PRL). This PRL contains information to assist the wireless device perform system selection and acquisition in 1x and 1x-EV-DO systems, particularly when the wireless device is roaming. The PRL identifies “permitted” systems that the wireless device should use and (optionally) “forbidden” systems that the wireless device should not use.
The PRL format for 1x is described in a document TIA/ELA/IS-683-A, entitled “Over-the-Air Service Provisioning of Mobile Stations in Spread Spectrum Standards,” June 1998, which is publicly available. The PRL format for 1x-EV-DO is described in a document TIA-683-C, entitled “Over-the-Air Service Provisioning of Mobile Stations in Spread Spectrum Standards,” March 2003, which is also publicly available. TIA-683-C defines (1) a PRL format that is based on IS-683-A and can convey PRL information for 1x systems and (2) an extended PRL format that can convey PRL information for both 1x and 1xEV-DO systems. TIA-683-C is backward compatible with IS-683-A.
A wireless device that stores an extended PRL is able to select and acquire 1x and 1x-EV-DO systems. However, the wireless device would not be able to select and acquire other systems not covered by TIA-683-C.